OpenRaiser/Intern-Atlas huggingface dataset:
Optimal Multi-Dimensional Mechanism Design: Reducing Revenue to Welfare Maximization
Venue: arXiv cs.GT 2012
Year: 2012

We provide a reduction from revenue maximization to welfare maximization in multi-dimensional Bayesian auctions with arbitrary (possibly combinatorial) feasibility constraints and independent bidders with arbitrary (possibly combinatorial) demand constraints, appropriately extending Myerson's result to this setting. We also show that every feasible Bayesian auction can be implemented as a distribution over virtual VCG allocation rules. A virtual VCG allocation rule has the following simple form: Every bidder's type t_i is transformed into a virtual type f_i(t_i), via a bidder-specific function. Then, the allocation maximizing virtual welfare is chosen. Using this characterization, we show how to find and run the revenue-optimal auction given only black box access to an implementation of the VCG allocation rule. We generalize this result to arbitrarily correlated bidders, introducing the notion of a second-order VCG allocation rule. We obtain our reduction from revenue to welfare optimization via two algorithmic results on reduced forms in settings with arbitrary feasibility and demand constraints. First, we provide a separation oracle for determining feasibility of a reduced form. Second, we provide a geometric algorithm to decompose any feasible reduced form into a distribution over virtual VCG allocation rules. In addition, we show how to execute both algorithms given only black box access to an implementation of the VCG allocation rule. Our results are computationally efficient for all multi-dimensional settings where the bidders are additive. In this case, our mechanisms run in time polynomial in the total number of bidder types, but not type profiles. For generic correlated distributions, this is the natural description complexity of the problem. The runtime can be further improved to poly(#items, #bidders) in item-symmetric settings by making use of recent techniques.
An analysis of social network connect services
Venue: arXiv cs.SE 2012
Year: 2012

Social network platforms are increasingly becoming identity providers and a media for showing multiple types of activity from third-party web sites. In this article, we analyze the services provided by seven of the most popular social network platforms. Results show OAuth emerging as the authentication and authorization protocol, giving support to three types of APIs, client-side or Javascript, server-side or representational state transfer (REST) and streaming. JSON is the most popular format, but there a considerable variety of resource types and a lack of representation standard, which makes harder for the third-party developer integrating with several services.
Beyond Max-Cut: λ-Extendible Properties Parameterized Above the Poljak-Turzík Bound
Venue: arXiv cs.DS 2012
Year: 2012

Poljak and Turzík (Discrete Math. 1986) introduced the notion of λ-extendible properties of graphs as a generalization of the property of being bipartite. They showed that for any 0<λ<1 and λ-extendible property Π, any connected graph G on n vertices and m edges contains a subgraph H \in Π with at least λm+ (1-λ)/2 (n-1) edges. The property of being bipartite is 1/2-extendible, and thus this bound generalizes the Edwards-Erdős bound for Max-Cut. We define a variant, namely strong λ-extendibility, to which the bound applies. For a strongly λ-extendible graph property Π, we define the parameterized Above Poljak- Turzík (APT) (Π) problem as follows: Given a connected graph G on n vertices and m edges and an integer parameter k, does there exist a spanning subgraph H of G such that H \in Π and H has at least λm + (1-λ)/2 (n - 1) + k edges? The parameter is k, the surplus over the number of edges guaranteed by the Poljak-Turzík bound. We consider properties Π for which APT (Π) is fixed- parameter tractable (FPT) on graphs which are O(k) vertices away from being a graph in which each block is a clique. We show that for all such properties, APT (Π) is FPT for all 0<λ<1. Our results hold for properties of oriented graphs and graphs with edge labels. Our results generalize the result of Crowston et al. (ICALP 2012) on Max-Cut parameterized above the Edwards-Erdős bound, and yield FPT algorithms for several graph problems parameterized above lower bounds, e.g., Max q-Colorable Subgraph problem. Our results also imply that the parameterized above-guarantee Oriented Max Acyclic Digraph problem is FPT, thus solving an open question of Raman and Saurabh (Theor. Comput. Sci. 2006).
A New Training Algorithm for Kanerva's Sparse Distributed Memory
Venue: arXiv cs.CV 2012
Year: 2012

The Sparse Distributed Memory proposed by Pentii Kanerva (SDM in short) was thought to be a model of human long term memory. The architecture of the SDM permits to store binary patterns and to retrieve them using partially matching patterns. However Kanerva's model is especially efficient only in handling random data. The purpose of this article is to introduce a new approach of training Kanerva's SDM that can handle efficiently non-random data, and to provide it the capability to recognize inverted patterns. This approach uses a signal model which is different from the one proposed for different purposes by Hely, Willshaw and Hayes in [4]. This article additionally suggests a different way of creating hard locations in the memory despite the Kanerva's static model.
Measuring Similarity in Large-scale Folksonomies
Venue: arXiv cs.IR 2012
Year: 2012

Social (or folksonomic) tagging has become a very popular way to describe content within Web 2.0 websites. Unlike taxonomies, which overimpose a hierarchical categorisation of content, folksonomies enable end-users to freely create and choose the categories (in this case, tags) that best describe some content. However, as tags are informally defined, continually changing, and ungoverned, social tagging has often been criticised for lowering, rather than increasing, the efficiency of searching, due to the number of synonyms, homonyms, polysemy, as well as the heterogeneity of users and the noise they introduce. To address this issue, a variety of approaches have been proposed that recommend users what tags to use, both when labelling and when looking for resources. As we illustrate in this paper, real world folksonomies are characterized by power law distributions of tags, over which commonly used similarity metrics, including the Jaccard coefficient and the cosine similarity, fail to compute. We thus propose a novel metric, specifically developed to capture similarity in large-scale folksonomies, that is based on a mutual reinforcement principle: that is, two tags are deemed similar if they have been associated to similar resources, and vice-versa two resources are deemed similar if they have been labelled by similar tags. We offer an efficient realisation of this similarity metric, and assess its quality experimentally, by comparing it against cosine similarity, on three large-scale datasets, namely Bibsonomy, MovieLens and CiteULike.
Quid Pro Quo: A Mechanism for Fair Collaboration in Networked Systems
Venue: arXiv cs.GT 2012
Year: 2012

Collaboration may be understood as the execution of coordinated tasks (in the most general sense) by groups of users, who cooperate for achieving a common goal. Collaboration is a fundamental assumption and requirement for the correct operation of many communication systems. The main challenge when creating collaborative systems in a decentralized manner is dealing with the fact that users may behave in selfish ways, trying to obtain the benefits of the tasks but without participating in their execution. In this context, Game Theory has been instrumental to model collaborative systems and the task allocation problem, and to design mechanisms for optimal allocation of tasks. In this paper, we revise the classical assumptions and propose a new approach to this problem. First, we establish a system model based on heterogenous nodes (users, players), and propose a basic distributed mechanism so that, when a new task appears, it is assigned to the most suitable node. The classical technique for compensating a node that executes a task is the use of payments (which in most networks are hard or impossible to implement). Instead, we propose a distributed mechanism for the optimal allocation of tasks without payments. We prove this mechanism to be robust event in the presence of independent selfish or rationally limited players. Additionally, our model is based on very weak assumptions, which makes the proposed mechanisms susceptible to be implemented in networked systems (e.g., the Internet).
Kolmogorov Complexity: Clustering Objects and Similarity
Venue: arXiv cs.CC 2012
Year: 2012

The clustering objects has become one of themes in many studies, and do not few researchers use the similarity to cluster the instances automatically. However, few research consider using Kommogorov Complexity to get information about objects from documents, such as Web pages, where the rich information from an approach proved to be difficult to. In this paper, we proposed a similarity measure from Kolmogorov Complexity, and we demonstrate the possibility of exploiting features from Web based on hit counts for objects of Indonesia Intellectual.
On When and How to use SAT to Mine Frequent Itemsets
Venue: arXiv cs.AI 2012
Year: 2012

A new stream of research was born in the last decade with the goal of mining itemsets of interest using Constraint Programming (CP). This has promoted a natural way to combine complex constraints in a highly flexible manner. Although CP state-of-the-art solutions formulate the task using Boolean variables, the few attempts to adopt propositional Satisfiability (SAT) provided an unsatisfactory performance. This work deepens the study on when and how to use SAT for the frequent itemset mining (FIM) problem by defining different encodings with multiple task-driven enumeration options and search strategies. Although for the majority of the scenarios SAT-based solutions appear to be non-competitive with CP peers, results show a variety of interesting cases where SAT encodings are the best option.
Computing optimal k-regret minimizing sets with top-k depth contours
Venue: arXiv cs.DB 2012
Year: 2012

Regret minimizing sets are a very recent approach to representing a dataset D with a small subset S of representative tuples. The set S is chosen such that executing any top-1 query on S rather than D is minimally perceptible to any user. To discover an optimal regret minimizing set of a predetermined cardinality is conjectured to be a hard problem. In this paper, we generalize the problem to that of finding an optimal k$regret minimizing set, wherein the difference is computed over top-k queries, rather than top-1 queries. We adapt known geometric ideas of top-k depth contours and the reverse top-k problem. We show that the depth contours themselves offer a means of comparing the optimality of regret minimizing sets using L2 distance. We design an O(cn^2) plane sweep algorithm for two dimensions to compute an optimal regret minimizing set of cardinality c. For higher dimensions, we introduce a greedy algorithm that progresses towards increasingly optimal solutions by exploiting the transitivity of L2 distance.
The Entropy Power Inequality and Mrs. Gerber's Lemma for Abelian Groups of Order 2^n
Venue: arXiv cs.IT 2012
Year: 2012

Shannon's Entropy Power Inequality can be viewed as characterizing the minimum differential entropy achievable by the sum of two independent random variables with fixed differential entropies. The entropy power inequality has played a key role in resolving a number of problems in information theory. It is therefore interesting to examine the existence of a similar inequality for discrete random variables. In this paper we obtain an entropy power inequality for random variables taking values in an abelian group of order 2^n, i.e. for such a group G we explicitly characterize the function f_G(x,y) giving the minimum entropy of the sum of two independent G-valued random variables with respective entropies x and y. Random variables achieving the extremum in this inequality are thus the analogs of Gaussians in this case, and these are also determined. It turns out that f_G(x,y) is convex in x for fixed y and, by symmetry, convex in y for fixed x. This is a generalization to abelian groups of order 2^n of the result known as Mrs. Gerber's Lemma.
About the Linear Complexity of Ding-Hellesth Generalized Cyclotomic Binary Sequences of Any Period
Venue: arXiv cs.IT 2012
Year: 2012

We defined sufficient conditions for designing Ding-Helleseth sequences with arbitrary period and high linear complexity for generalized cyclotomies. Also we discuss the method of computing the linear complexity of Ding-Helleseth sequences in the general case.
Sketch \star-metric: Comparing Data Streams via Sketching
Venue: arXiv cs.DS 2012
Year: 2012

In this paper, we consider the problem of estimating the distance between any two large data streams in small- space constraint. This problem is of utmost importance in data intensive monitoring applications where input streams are generated rapidly. These streams need to be processed on the fly and accurately to quickly determine any deviance from nominal behavior. We present a new metric, the Sketch \star-metric, which allows to define a distance between updatable summaries (or sketches) of large data streams. An important feature of the Sketch \star-metric is that, given a measure on the entire initial data streams, the Sketch \star-metric preserves the axioms of the latter measure on the sketch (such as the non-negativity, the identity, the symmetry, the triangle inequality but also specific properties of the f-divergence). Extensive experiments conducted on both synthetic traces and real data allow us to validate the robustness and accuracy of the Sketch \star-metric.
Covering Rough Sets From a Topological Point of View
Venue: arXiv cs.DB 2012
Year: 2012

Covering-based rough set theory is an extension to classical rough set. The main purpose of this paper is to study covering rough sets from a topological point of view. The relationship among upper approximations based on topological spaces are explored.
Diversity in Ranking using Negative Reinforcement
Venue: arXiv cs.IR 2012
Year: 2012

In this paper, we consider the problem of diversity in ranking of the nodes in a graph. The task is to pick the top-k nodes in the graph which are both 'central' and 'diverse'. Many graph-based models of NLP like text summarization, opinion summarization involve the concept of diversity in generating the summaries. We develop a novel method which works in an iterative fashion based on random walks to achieve diversity. Specifically, we use negative reinforcement as a main tool to introduce diversity in the Personalized PageRank framework. Experiments on two benchmark datasets show that our algorithm is competitive to the existing methods.
Information-Theoretic Study on Routing Path Selection in Two-Way Relay Networks
Venue: arXiv cs.IT 2012
Year: 2012

Two-way relaying is a promising technique to improve network throughput. However, how to apply it to a wireless network remains an unresolved issue. Particularly, challenges lie in the joint design between the physical layer and the routing protocol. Applying an existing routing protocol to a two-way relay network can easily compromise the advantages of two-way relaying. Considering routing path selection and two-way relaying together can be formulated as a network optimization problem, but it is usually NP-hard. In this paper, we take a different approach to study routing path selection for two-way relay networks. Instead of solving the joint optimization problem, we study the fundamental characteristics of a routing path consisting of multihop two-way relaying nodes. Information theoretical analysis is carried out to derive bandwidth efficiency and energy efficiency of a routing path in a two-way relay network. Such analysis provides a framework of routing path selection by considering bandwidth efficiency, energy efficiency and latency subject to physical layer constraints such as the transmission rate, transmission power, path loss exponent, path length, and the number of relays. This framework provides insightful guidelines on routing protocol design of a two-way relay network. Our analytical framework and insights are illustrated by extensive numerical results.
Model-Lite Case-Based Planning
Venue: arXiv cs.AI 2012
Year: 2012

There is increasing awareness in the planning community that depending on complete models impedes the applicability of planning technology in many real world domains where the burden of specifying complete domain models is too high. In this paper, we consider a novel solution for this challenge that combines generative planning on incomplete domain models with a library of plan cases that are known to be correct. While this was arguably the original motivation for case-based planning, most existing case-based planners assume (and depend on) from-scratch planners that work on complete domain models. In contrast, our approach views the plan generated with respect to the incomplete model as a "skeletal plan" and augments it with directed mining of plan fragments from library cases. We will present the details of our approach and present an empirical evaluation of our method in comparison to a state-of-the-art case-based planner that depends on complete domain models.
Modeling Enhancements in DSR, FSR, OLSR under Mobility and Scalability Constraints in VANETs
Venue: arXiv cs.NI 2012
Year: 2012

Frequent topological changes due to high mobility is one of the main issues in Vehicular Ad-hoc NETworks (VANETs). In this paper, we model transmission probabilities of 802.11p for VANETs and effect of these probabilities on average transmission time. To evaluate the effect of these probabilities of VANETs in routing protocols, we select Dynamic Source Routing (DSR), Fish-eye State Routing (FSR) and Optimized Link State Routing (OLSR). Framework of these protocols with respect to their packet cost is also presented in this work. A novel contribution of this work is enhancement of chosen protocols to obtain efficient behavior. Extensive simulation work is done to prove and compare the efficiency in terms of high throughput of enhanced versions with default versions of protocols in NS-2. For this comparison, we choose three performance metrics; throughput, End-to-End Delay (E2ED) and Normalized Routing Load (NRL) in different mobilities and scalabilities. Finally, we deduce that enhanced DSR (DSR-mod) outperforms other protocols by achieving 16% more packet delivery for all scalabilities and 28% more throughput in selected mobilities than original version of DSR (DSR-orig).
Wireless Scheduling with Dominant Interferers and Applications to Femtocellular Interference Cancellation
Venue: arXiv cs.IT 2012
Year: 2012

We consider a general class of wireless scheduling and resource allocation problems where the received rate in each link is determined by the actions of the transmitter in that link along with a single dominant interferer. Such scenarios arise in a range of scenarios, particularly in emerging femto- and picocellular networks with strong, localized interference. For these networks, a utility maximizing scheduler based on loopy belief propagation is presented that enables computationally-efficient local processing and low communication overhead. Our main theoretical result shows that the fixed points of the method are provably globally optimal for arbitrary (potentially non-convex) rate and utility functions. The methodology thus provides globally optimal solutions to a large class of inter-cellular interference coordination problems including subband scheduling, dynamic orthogonalization and beamforming whenever the dominant interferer assumption is valid. The paper focuses on applications for systems with interference cancellation (IC) and suggests a new scheme on optimal rate control, as opposed to traditional power control. Simulations are presented in industry standard femtocellular network models demonstrate significant improvements in rates over simple reuse 1 without IC, and near optimal performance of loopy belief propagation for rate selection in only one or two iterations.
JASF: Jasta Security Framework
Venue: arXiv cs.CR 2012
Year: 2012

JASM is a model designed to increase the security level in authentication systems. It uses IP Address of the user in the authentication process to enhance the security.
A robust l_1 penalized DOA estimator
Venue: arXiv cs.IT 2012
Year: 2012

The SPS-LASSO has recently been introduced as a solution to the problem of regularization parameter selection in the complex-valued LASSO problem. Still, the dependence on the grid size and the polynomial time of performing convex optimization technique in each iteration, in addition to the deficiencies in the low noise regime, confines its performance for Direction of Arrival (DOA) estimation. This work presents methods to apply LASSO without grid size limitation and with less complexity. As we show by simulations, the proposed methods loose a negligible performance compared to the Maximum Likelihood (ML) estimator, which needs a combinatorial search We also show by simulations that compared to practical implementations of ML, the proposed techniques are less sensitive to the source power difference.
Temporal Reachability Graphs
Venue: arXiv cs.NI 2012
Year: 2012

While a natural fit for modeling and understanding mobile networks, time-varying graphs remain poorly understood. Indeed, many of the usual concepts of static graphs have no obvious counterpart in time-varying ones. In this paper, we introduce the notion of temporal reachability graphs. A (tau,delta)-reachability graph} is a time-varying directed graph derived from an existing connectivity graph. An edge exists from one node to another in the reachability graph at time t if there exists a journey (i.e., a spatiotemporal path) in the connectivity graph from the first node to the second, leaving after t, with a positive edge traversal time tau, and arriving within a maximum delay delta. We make three contributions. First, we develop the theoretical framework around temporal reachability graphs. Second, we harness our theoretical findings to propose an algorithm for their efficient computation. Finally, we demonstrate the analytic power of the temporal reachability graph concept by applying it to synthetic and real-life datasets. On top of defining clear upper bounds on communication capabilities, reachability graphs highlight asymmetric communication opportunities and offloading potential.
Security of the DNS Protocol - Implementation and Weaknesses Analyses of DNSSEC
Venue: arXiv cs.CR 2012
Year: 2012

Today, Internet offers many critical applications. So, it becomes very crucial for Internet service providers to ensure traceability of operations and to secure data exchange. Since all these communications are based on the use of the Domain Name System (DNS) protocol, it becomes necessary to think to enhance and secure it by proposing a secure version of this protocol that can correct the whole or a part of the DNS protocol weaknesses and vulnerabilities. In this context, DNSsec was created by the IETF to ensure the integrity of DNS data and authentication of the source of such data. DNSsec is based on the key cryptography public to provide different security services. In the present paper, we will present first the DNS protocol and its weaknesses. After that, we will be interested in studying the DNSsec implementation and data exchange, and then give a deep analysis of its weaknesses.